/**   
* Hash算法大全<br>   
* 推荐使用FNV1算法   
* @algorithm None   
* @author Goodzzp 2006-11-20   
* @lastEdit Goodzzp 2006-11-20    
* @editDetail Create   
*/   
public class HashAlgorithms    
{    
    /**   
    * 加法hash   
    * @param key 字符串   
    * @param prime 一个质数   
    * @return hash结果   
    */   
    public static int additiveHash(String key, int prime)    
    {    
       int hash, i;    
       for (hash = key.length(), i = 0; i < key.length(); i++)    
        hash += key.charAt(i);    
       return (hash % prime);    
    }    
       
    /**   
    * 旋转hash   
    * @param key 输入字符串   
    * @param prime 质数   
    * @return hash值   
    */   
    public static int rotatingHash(String key, int prime)    
    {    
       int hash, i;    
       for (hash=key.length(), i=0; i<key.length(); ++i)    
         hash = (hash<<4)^(hash>>28)^key.charAt(i);    
       return (hash % prime);    
    //   return (hash ^ (hash>>10) ^ (hash>>20));    
    }    
       
    // 替代：    
    // 使用：hash = (hash ^ (hash>>10) ^ (hash>>20)) & mask;    
    // 替代：hash %= prime;    
       
       
    /**   
    * MASK值，随便找一个值，最好是质数   
    */   
    static int M_MASK = 0x8765fed1;    
    /**   
    * 一次一个hash   
    * @param key 输入字符串   
    * @return 输出hash值   
    */   
    public static int oneByOneHash(String key)    
    {    
       int   hash, i;    
       for (hash=0, i=0; i<key.length(); ++i)    
       {    
         hash += key.charAt(i);    
         hash += (hash << 10);    
         hash ^= (hash >> 6);    
       }    
       hash += (hash << 3);    
       hash ^= (hash >> 11);    
       hash += (hash << 15);    
    //   return (hash & M_MASK);    
       return hash;    
    }    
       
    /**   
    * Bernstein's hash   
    * @param key 输入字节数组   
    * @param level 初始hash常量   
    * @return 结果hash   
    */   
    public static int bernstein(String key)    
    {    
       int hash = 0;    
       int i;    
       for (i=0; i<key.length(); ++i) hash = 33*hash + key.charAt(i);    
       return hash;    
    }    
       
    //    
    //// Pearson's Hash    
    // char pearson(char[]key, ub4 len, char tab[256])    
    // {    
    //   char hash;    
    //   ub4 i;    
    //   for (hash=len, i=0; i<len; ++i)     
    //     hash=tab[hash^key[i]];    
    //   return (hash);    
    // }    
       
    //// CRC Hashing，计算crc,具体代码见其他    
    // ub4 crc(char *key, ub4 len, ub4 mask, ub4 tab[256])    
    // {    
    //   ub4 hash, i;    
    //   for (hash=len, i=0; i<len; ++i)    
    //     hash = (hash >> 8) ^ tab[(hash & 0xff) ^ key[i]];    
    //   return (hash & mask);    
    // }    
       
    /**   
    * Universal Hashing   
    */   
    public static int universal(char[]key, int mask, int[] tab)    
    {    
       int hash = key.length, i, len = key.length;    
       for (i=0; i<(len<<3); i+=8)    
       {    
         char k = key[i>>3];    
         if ((k&0x01) == 0) hash ^= tab[i+0];    
         if ((k&0x02) == 0) hash ^= tab[i+1];    
         if ((k&0x04) == 0) hash ^= tab[i+2];    
         if ((k&0x08) == 0) hash ^= tab[i+3];    
         if ((k&0x10) == 0) hash ^= tab[i+4];    
         if ((k&0x20) == 0) hash ^= tab[i+5];    
         if ((k&0x40) == 0) hash ^= tab[i+6];    
         if ((k&0x80) == 0) hash ^= tab[i+7];    
       }    
       return (hash & mask);    
    }    
       
    /**   
    * Zobrist Hashing   
    */     
    public static int zobrist( char[] key,int mask, int[][] tab)    
    {    
       int hash, i;    
       for (hash=key.length, i=0; i<key.length; ++i)    
         hash ^= tab[i][key[i]];    
       return (hash & mask);    
    }    
       
    // LOOKUP3     
    // 见Bob Jenkins(3).c文件    
       
    // 32位FNV算法    
    static int M_SHIFT = 0;    
    /**   
    * 32位的FNV算法   
    * @param data 数组   
    * @return int值   
    */   
    public static int FNVHash(byte[] data)    
    {    
        int hash = (int)2166136261L;    
        for(byte b : data)    
            hash = (hash * 16777619) ^ b;    
        if (M_SHIFT == 0)    
            return hash;    
        return (hash ^ (hash >> M_SHIFT)) & M_MASK;    
    }    
    /**   
     * 改进的32位FNV算法1   
     * @param data 数组   
     * @return int值   
     */   
    public static int FNVHash1(byte[] data)    
    {    
        final int p = 16777619;    
        int hash = (int)2166136261L;    
        for(byte b:data)    
            hash = (hash ^ b) * p;    
        hash += hash << 13;    
        hash ^= hash >> 7;    
        hash += hash << 3;    
        hash ^= hash >> 17;    
        hash += hash << 5;    
        return hash;    
    }    
    /**   
     * 改进的32位FNV算法1   
     * @param data 字符串   
     * @return int值   
     */   
    public static int FNVHash1(String data)    
    {    
        final int p = 16777619;    
        int hash = (int)2166136261L;    
        for(int i=0;i<data.length();i++)    
            hash = (hash ^ data.charAt(i)) * p;    
        hash += hash << 13;    
        hash ^= hash >> 7;    
        hash += hash << 3;    
        hash ^= hash >> 17;    
        hash += hash << 5;    
        return hash;    
    }    
   
    /**   
     * Thomas Wang的算法，整数hash   
     */     
    public static int intHash(int key)    
    {    
      key += ~(key << 15);    
      key ^= (key >>> 10);    
      key += (key << 3);    
      key ^= (key >>> 6);    
      key += ~(key << 11);    
      key ^= (key >>> 16);    
      return key;    
    }    
    /**   
     * RS算法hash   
     * @param str 字符串   
     */   
    public static int RSHash(String str)    
    {    
        int b    = 378551;    
        int a    = 63689;    
        int hash = 0;    
   
       for(int i = 0; i < str.length(); i++)    
       {    
          hash = hash * a + str.charAt(i);    
          a    = a * b;    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
    /* End Of RS Hash Function */   
   
    /**   
     * JS算法   
     */   
    public static int JSHash(String str)    
    {    
       int hash = 1315423911;    
   
       for(int i = 0; i < str.length(); i++)    
       {    
          hash ^= ((hash << 5) + str.charAt(i) + (hash >> 2));    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
    /* End Of JS Hash Function */   
   
    /**   
     * PJW算法   
     */   
    public static int PJWHash(String str)    
    {    
        int BitsInUnsignedInt = 32;    
        int ThreeQuarters     = (BitsInUnsignedInt * 3) / 4;    
        int OneEighth         = BitsInUnsignedInt / 8;    
        int HighBits          = 0xFFFFFFFF << (BitsInUnsignedInt - OneEighth);    
        int hash              = 0;    
        int test              = 0;    
   
       for(int i = 0; i < str.length();i++)    
       {    
          hash = (hash << OneEighth) + str.charAt(i);    
   
          if((test = hash & HighBits) != 0)    
          {    
             hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));    
          }    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
    /* End Of P. J. Weinberger Hash Function */   
   
    /**   
     * ELF算法   
     */   
    public static int ELFHash(String str)    
    {    
        int hash = 0;    
        int x    = 0;    
   
       for(int i = 0; i < str.length(); i++)    
       {    
          hash = (hash << 4) + str.charAt(i);    
          if((x = (int)(hash & 0xF0000000L)) != 0)    
          {    
             hash ^= (x >> 24);    
             hash &= ~x;    
          }    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
    /* End Of ELF Hash Function */   
   
    /**   
     * BKDR算法   
     */   
    public static int BKDRHash(String str)    
    {    
        int seed = 131; // 31 131 1313 13131 131313 etc..    
        int hash = 0;    
   
       for(int i = 0; i < str.length(); i++)    
       {    
          hash = (hash * seed) + str.charAt(i);    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
    /* End Of BKDR Hash Function */   
   
    /**   
     * SDBM算法   
     */   
    public static int SDBMHash(String str)    
    {    
        int hash = 0;    
   
       for(int i = 0; i < str.length(); i++)    
       {    
          hash = str.charAt(i) + (hash << 6) + (hash << 16) - hash;    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
    /* End Of SDBM Hash Function */   
   
    /**   
     * DJB算法   
     */   
    public static int DJBHash(String str)    
    {    
       int hash = 5381;    
   
       for(int i = 0; i < str.length(); i++)    
       {    
          hash = ((hash << 5) + hash) + str.charAt(i);    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
    /* End Of DJB Hash Function */   
   
    /**   
     * DEK算法   
     */   
    public static int DEKHash(String str)    
    {    
        int hash = str.length();    
   
       for(int i = 0; i < str.length(); i++)    
       {    
          hash = ((hash << 5) ^ (hash >> 27)) ^ str.charAt(i);    
       }    
   
       return (hash & 0x7FFFFFFF);    
    }    
}
